Each year the species travels more than 600 miles (1,000 kilometers) from the South China Sea up the Mekong River (see a map of the region).

"This is similar to many salmon species that spend the first part of their lives at sea and then migrate hundreds—or even thousands—of miles up coastal rivers to spawn," said Zeb Hogan, a fisheries biologist with the University of Nevada in Reno.

Hogan is a co-author of the new study, which appears in this month's issue of the Journal of Fish Biology.

Heok Hee Ng, a fish biologist at the National University of Singapore who was not involved in the study, said that the findings show that catfish are not "inactive dullards" after all.

"It certainly should change the way the general public looks at catfish," he said.

The new findings also suggest that related catfish species all over the world may be more migratory than previously thought.

Conservationists warn that a proposed hydroelectric dam on the Mekong in Laos could have a devastating impact on the river's many catfish species.

"There is clear evidence that Hou Sahong—the proposed site for the Khone Falls dam—is a major corridor for migratory fish and one of the worst possible locations in the entire basin to build a dam," Hogan said.

Connecting the Dots

Catfish are named for their prominent barbels, organs near their mouths that resemble a cat's whiskers. Thousands of catfish species swim Earth's rivers and streams, including some of the largest and smallest freshwater fish on the planet.